Rotary tube for crimping filamentary synthetic fibers by imparting thereto a false twist

ABSTRACT

A false-twist tube has the twist imparting means, for example a pin, located substantially midway between the ends of the tube, there being a transverse aperture or bore to enable the yarn which is to be false twisted to be passed about the pin.  The tube is provided with a central portion of larger diameter than the rest of the tube and which is magnetically urged against the driving discs.  The central portion may be formed integrally with the rest of the tube, or tubular portions of tool steel may be press-fitted in a central portion of alloy steel.

Jan. 16, 1968 K. SCHWABE ETAL 3,363,409

ROTARY TUBE FOR CRIMPII G FILAMENTARY SYNTHETIC FIBERS BY IMPARTINGTHERETO A FALSE TWIST Filed Jan. 29, 1965 FIG. 7 FIGZ I m an ers E 1 b#15190 rneys United States Patent 3 Claims. oi. 57-77:

For the purpose of imparting a false twist to filamentary syntheticfibers and thus crimping the said fibers, there has been proposed theuse of rotary tubes provided with a twist-inducing arrangement. Thus farit has been conventional to construct such twisting tubes in the mannershown in FIG. 1 of the appended drawings. The thread or yarn 1 to becrimped is guided through the longitudinal bore 2 of the tube body shownin longitudinal cross-section in FIG. 1; the central portion 3 of thetube having a wall of relatively large thickness is provided at its endswith annular pole shoes 4 and 5. For the purpose of crimping the saidfilamentary yarn 1, the central portion 3 of the tube body is urgedagainst pairs of friction discs (not shown) by the action of magneticforces which are produced by a magnetic stator body (not shown) and actupon the pole shoes 4 and 5 of the central portion 3 of that part of thetube which, together with the central portion, constitutes a magneticarmature body. The terminal portions 6 and 7 of the tube which are ofsmaller wall thickness than the central portion receive the filamentwhere it enters and leaves, respectively, the bore of tube. Connected tothe terminal portion 7 on the exit end of the tube is a bifurcation 8which carries, as a means to impart the desired twist to the filament, apin 9 extending transversely of the axis of the tube and wrapped by thefilament to be twisted. During operation of the tube the filament willform a balloon 11 extending between the twist imparting means 9 and apigtail guide 10.

FIG. 1 illustrates the most Widely adopted known construction of arotary tube serving to impart a false twist to filamentary yarns ofsynthetic material for the purpose of crimping them. Besides theconstruction of FIG. 1, there has also become known a construction inwhich the twist imparting means 9 are not arranged in the manner shownin FIG. 1, i.e. at the point at which the filament 1 emerges from thetube, that is to say, at the free end of the tubular terminal portion 7,but at the entry end thereof, i.e. at the free end of the tubularterminal portion 6 of the tube.

These two known arrangements of the twist imparting means in rotarytubes serving to impart a false twist to filamentary yarns suffer from adrawback in that the said bifurcation (carrying the reference numeral 8in FIG. 1) of the twist imparting means which is required to permit thethreading of the yarn is subject to distortion by the large centrifugalforces caused by the high speed of the tube which in some cases maygreatly exceed 200,000 revolutions per minute, this distortion caus- 6ing the twist imparting pin, such as shown at 9 in FIG. 1, to work loosein their retaining holes, to be bent out of shape or to be broken.Another drawback inherent in the known arrangement of the twistimparting means at the free end of the rotary tube is to be seen in thefact that yarn balloons of different size are formed upstream anddownstream of the twist imparting pins. The different size of theseballoons is the result of the fact that the balloon formed at theentrance of the bore of the tube is constrained by the wall of the bore,whereas the other balloon formed at the exit of the tube is notsubjected to any such restraint. These different conditions prevailingin the entry and exit regions of the thread result in the setting-up ofundesirable stresses in the thread, such stresses tending to promoteslippage of the thread in relation to the twist imparting pin andinterfering with the accumulation of twist turns at the said pin, theresult being that there occur in the running yarn portions in which thetwist has not been removed by an untwisting action. I

The aforedescribed drawbacks inherent in rotary tubes incorporatingtwist imparting means serving to impart a false twist to filamentarysynthetic fibers to be crimped are obviated according to the inventionby the arrangement of the twist imparting means at a point which isequidistant from the yarn entry and exit zones and by the provision ofan aperture extending transversely of the axis of the rotary tube, thetwist imparting means being disposed in the said aperture which permitsthe yarn to be threaded through the tube. This arrangement ensures thatthe quality of the crimped yarn is no longer reduced by the presence ofnon-uniform stresses, this permitting the production of crimped yarns ofhigh and uniform quality.

According to another feature of the invention, there may be provided anarmature body made of alloy steel having a longitudinal bore into theends of which are inserted press-fitted tubular bearing members made oftool steel. This arrangement ensures that the rotary tube made of steelwhich in operation rotates in a magnetic field whereby it is subjectedto the action of eddy currents will not be heated to an undesirableextent at the high rotary speeds required. The use of alloy steel in thearmature body of the rotary tube, i.e. in its central portion and thetwo annular pole shoes, makes it possible to limit the heating of thetube to a low value without interfering with the desired mechanical andmagnetic conditions. Since the said tubular bearing members made of toolsteel are press-fitted in the free ends of the armature body it is nolonger necessary to perform the ditlicult machining operation ofproviding a narrow longitudinal bore in the bearing members.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawing, illustrating a preferred embodiment of theinvention, wherein:

FIG. 1 is a longitudinal cross-sectional view of a rotary tube of knowndesign;

FIGS. 2 and 3 are longitudinal cross-sectional views of two differentembodiments of the invention in which the rotary tube is of single-piececonstruction and made of steel;

FIG. 4 is a longitudinal cross-sectional view of a third embodiment inwhich the armature body consists of alloy steel, whereas the tubularbearing members are made of tool steel.

As shown in FIG. 2, the armature body 24 of the rotary tube is providedcentrally between its ends with an aperture 12 extending transversely ofits longitudinal axis. A twist imparting pin 13 extends perpendicularlyto both the axis of the rotary tube and the axis of aperture 12, theaperture making it possible to wrap the yarn 14 to be twisted around thepin 13. The arrangement of the twist imparting means 13 at substantiallyequal distances from the entry end 15 and the exit end 16 of the rotarytube provides for the advantages mentioned earlier, these advantagesresulting in the aforementioned increase in the quality of the crimpedyarn.

FIG. 3 is a longitudinal cross-sectional view extending at right anglesto the plane of the view shown in FIG.

2; in FIG. 3, the twist imparting pin 13 which is pressfitted in a boreof the armature body 24 extends transversely of the axis of the rotarytube. As indicated at 17 in FIG. 3, the twist imparting pin is providedwith a centrally located throat section to be Wrapped by the yarn to beimparted a false twist.

Shown in FIG. 4 vis another embodiment of the invention comprising anarmature body 18 made of alloy steel. The said armature body is providedWith a longitudinal bore 19 of relatively large diameter and With ashort transverse bore 20, the twist imparting pin 21 being pressfittedinto the bore 20. Press-fitted in each of the two terminal portions ofthe armature body 18 is a tubular bearing member 22, 23 made of toolsteel. The provision of these tubular bearing members aifords theadvantages indicated earlier in this specification.

What is claimed is:

1. An apparatus for twisting yarn comprising an armature body having alongitudinally extending bore through which the yarn passes and atransversely extending bore located substantially equidistant from theends of said body; and a yarn retaining member disposed in saidtransversely extending bore and extending at right angles to each ofsaid bores, said member being adapted to receive said yarn to fix samewith respect to said armature body, so that upon rotation of said bodyabout its longitudinal axis, a twist will be imparted to said yarn.

2. The apparatus of claim 1, wherein said l0ngitudi nally extending boreis of a length sufiieient to eliminate ballooning of the yarn therein.

3. The apparatus of claim 1, wherein said armature body includes anouter portion of alloy steel and two tubular bearing members of toolsteel press fitted into the ends of said outer portion, said pin beingpress fitted into said transversely extending bore.

References Cited UNITED STATES PATENTS 2,557,104 6/1951 Hegedus 57-77332,659,193 11/1953 Hegedus 57-77.33 2,821,062 1/1958 Boillat et a1.5777.33 2,928,229 3/1960 Haas 5777.3 3,035,399 5/1962 Scragg 57-77.453,058,289 10/1962 Raschle 57-77.3 3,059,409 10/1962 Schussler 57-77.3 X3,090,190 5/1963 Bousso et al 5777.3 X 3,114,235 12/1963 Griset 57-773 XFOREIGN PATENTS 204,5 32 11/ 1956 Australia. 1,317,476 1/1963 France.1,362,081 4/ 1964 France.

925,261 5/ 1963 Great Britain.

' FRANK J. COHEN, Primary Examiner.

D. WATKINS, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,363,409 January 16 1969 Kurt Schwabe et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below Column 2, line 50, strike out "two differentembodiments" and insert instead an embodiment line 53, for "third" readsecond Signed and sealed this 22nd day of April 1969.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

1. AN APPARATUS FOR TWISTING YARN COMPRISING AN ARMATURE BODY HAVING ALONGITUDINALLY EXTENDING BORE THROUGH WHICH THE YARN PASSES AND ATRANSVERSELY EXTENDING BORE LOCATED SUBSTANTIALLY EQUIDISTANT FROM THEENDS OF SAID BODY; AND A YARN RETAINING MEMBER DISPOSED IN SAIDTRANSVERSELY EXTENDING BORE AND EXTENDING AT RIGHT ANGLES TO EACH OFSAID BORES, SAID MEMBER BEING ADAPTER TO RECEIVE SAID YARN TO FIX SAMEWITH RESPECT TO SAID ARMATURE BODY SO THAT UPON ROTATION OF SAID BODYABOUT ITS LONGITUDINAL AXIS, A TWIST WILL BY IMPARTED TO SAID YARN.